Black oil conversion product separation process



Feb. 1968 J. R. PENISTEN ETAL 3,371,030

BLACK OIL CONVERSION PRODUCT SEPARATION PROCESS Filed Dec. 30, 1966 Q EKI Eaz mm //V VE/V TORS J. Ruben Pen/si'en Bennett L A/wafer @8390 Eaau\suxuqmm mu A T TORNEYS United States Patent Ofilice 3,371,030 BLACK 01LCONVERSION PRODUCT SEPARATE'DN PRGCESS J. Robert Penisten, Palatine, andBennett L. Atwater, Elk

Grove Township, IlL, assignors to Universal Oil Prodnets Company, DesPlaines, Ili., a corporation of Delaware Filed Dec. 30, 1966, Ser. No.606,107 Claims. (Cl. 208-102) The present invention involves a processfor effecting the separation of a conversion product effluent, andparticularly encompasses the separation of a mixed phase producteffluent. More specifically, the inventive concept described herein isdirected toward a scheme for separating the hydrocarbonaceous producteffluent resulting from the conversion of a charge stock containing highmolecular weight hydrocarbons boiling above a temperature of about 1050F. This conversion product eflluent is in mixed phase, and generallycomprises hydrogen, and acid gas, ammonia, normally gaseous hydrocarbonsand normally liquid hydrocarbons.

Although the separation process is applicable to a hydrocarbonconversion process which may be broadly classified ashydrogen-consuming, it is most advantageous- 1y adaptable to a black oilconversion process. This conversion process employshydrocracking/hydrorefining techniques for the principal purposes of (1)reducing the concentration of various contaminating influences (sulfurand nitrogen-containing compounds as well as metallic complexes), and(2) to convert the heavy hydrocarbonaceous material into lower boilinghydrocarbon products reduced in the concentration of the foregoingcontaminants. Illustrative of hydrocarbonaceous material classified asblack oil are atmospheric tower bottoms products, vacuum tower bottomsproducts, crude oil residuum, topped crude oils, oils extracted from tarsands, etc.

Black oils, particularly those extracted from tar sands, atmospheric andvacuum residuum, contain high molecular weight sulfurous compounds,large quantities of nitrogenous compounds, high molecular weightorgano-metallic complexes, principally comprising nickel and vanadium,and a considerable quantity of asphaltic material insoluble in lowerboiling hydrocarbons such as pentane and/or heptane. An abundant supplyof such hydrocarbonaceous material currently exists, most of which has agravity API at 60 F., less than 20.0, and a significant proportion ofwhich has a gravity less than 100 API. Black oils are furthercharacterized in that the boiling range thereof indicates that 10.0% byvolume, or more, boils above a temperature of 1050 F. Although not knownaccurately, a large amount of black oil is currently available, and ischaracterized in that more than 50.0% by volume boils above atemperature of about 1050 F. The conversion of at least a portion ofsuch material into distillable hydrocarbons-4e. those boiling attemperatures below about1050" F.--has hitherto been economicallynonfeasible.

Specific examples of the black oils, a process for the conversion ofwhich advantageously utilizes the separation process of our invention,include a vacuum tower bottoms product having a gravity of 70 API at 60F., and containing 4.1% by weight of sulfur and 23.7% by weight ofasphaltics; a Middle-East crude oil having a gravity of 110 API at 60F., containing 10.1% by Weight of asphaltics and about 5.2% by weight ofsulfur; and a vacuum residuum having a gravity of 8.8 API at 60 F., andcontaining 3.0% by weight of sulfur and 4300 ppm. of nitrogen, andhaving a 20.0% volumetric distillation temperature of 1055 F. Ingeneral, the asphaltics are found to be colloidally dispersed in theblack oil, and, when subjected to elevated temperature,

3,371,030 Patented Feb. 27, 1968 have the tendency of flocculate andpolymerize, whereby the conversion thereof to more valuable oil-solubleproducts becomes extremely difficult. Thus, for example, the heavybottoms from a crude oil vacuum distillation column indicates aConradson Carbon Residue factor of 16.0% by weight.

A principal object of the present invention is to provide an improvedprocess for the separation of a conversion product eflluent containinghydrocarbonaceous material boiling above a temperature of about 1050 F.A corollary objective is to separate a conversion product effluentcontaining hydrogen, an acid gas, normally gaseous hydrocarbons andnormally liquid hydrocarbons at least some of which boil above atemperature of about 1050 F.

Another object of this invention is to atford a mixedphase conversionproduct effluent separation process in which the recovered normallyliquid hydrocarbons boiling below a temperature of 1050 F. aresubstantially completely free from those non-distillable hydrocarbonsboiling above about 1050 F.

Still another object of the present invention is to provide a separationprocess which produces an internally recycled wash oil used within theprocess to remove nondistillable asphaltics from equipment employedtherein.

These and other objects are achieved by the present invention as morecompletely described hereinbelow, and especially with reference to theaccompanying drawing which is a simplified representation of oneembodiment.

As hereinbefore stated, the conversion product effluent is inmixed-phase, and contains hydrogen, hydrogen sulfide, normally gaseoushydrocarbons including methane, ethane and propane, normally liquidgasoline boiling range hydrocarbons including pentane,.hexane andhydrocarbons boiling up to about 400 F., middle-distillate hydrocarbons,gas oil boiling range hydrocarbons, and hydrocarbonaceous materialboiling above 1050" F. 'In the present specification and appendedclaims, butanes will be considered in the classification of normallyliquid hydrocarbons since they are generally recovered as a desiredproduct due to their blending value with respect to motor fuel. Also,the term nondistillables is intended to connote those hydrocarbonshaving normal boiling points above about 1050", F. From this type ofproduct efiiuent, it is generally intended to recover or produce, atleast the following as product streams: (1) a 650 F.- plus hydrocarbonfraction suitable for use as fuel oil; (2) a 400 F.-650 F.middle-distillate fraction for use either as fuel oil, or as the chargestock to a hydrocracking unit designed for maximum LPG (liquifiedpetroleum gas) production; (3) a gasoline boiling range fraction whichmay or may not contain butanes and pentanes; (4) a butane-pentaneconcentrate for use as a motor fuel blending component, or as the chargestock to an isomerization unit; (5) a hydrogernrich gaseous phase to berecycled to the conversion zone to supply a portion of the hydrogenconsumed therein; and, (6) a fuel gas waste product comprising methaneand ethane, and being substantially free from the more valuable heavierhydrocanbons.

Usually, the mixed-phase conversion zone effluent is introduced, aftersubstantial cooling, into a high-pressure, low temperature separator inorder to recover unreacted hydrogen for use as an internal recyclestream within the process, followed by subsequent separation andrecovery of distillable hydrocarbon products through the use ofdistillation and/or fractionation means. Such a scheme suffers from atleast two drawbacks when the conversion product effluent results fromthe hydrocracking/hydrorefining of black oils. Large quantities ofhydrogen and normally gaseous hydrocarbons are in the product effiuent,and the normally liquid hydrocarbon portion thereof has a highabsorption capacity for such material. The conversion product effluentalso contains the unreacted non-distillables (1050 F.-plus material),generally referred to as residuum, which material has the tendency tocause plugging of various lines and equipment. The present invention isprimarily concerned with the latter problem and with the solution of theprocessing difliculties which stem therefrom.

Therefore, in a broad embodiment, the present invention relates to aprocess for separating a mixed-phase hydrocarbonaceous conversionproduct efiluent containing hydrocarbons boiling above about 1050 F.(asphaltic non-distillables), which process comprises the steps of: (a)separating said product eflluent in a first separation zone at atemperature above about 700 F. and a pressure above about 1000 p.s.i.g.,to provide a first vapor phase and a first liquid phase containingasphaltics; (b) condensing said first vapor phase and separating thecondensed vapors in a second separation zone at a tempera ture belowabout 140 F. and a pressure susbtantially the same as said firstseparation zone, to provide a hydrogen-rich second vapor phase and asecond liquid phase principally comprising propane and heavier normallyliquid hydrocarbons; (c) introducing at least a portion of said firstliquid phase into a third separation zone at a point below a meshblanket disposed within said third separation zone, at a temperaturesubstantially the same as said first separation zone and a pressure lessthan about 200 p.s.i.g., to provide a third vapor phase and a thirdliquid phase containing hydrocarbons boiling above 1050 F.; (d) furtherseparating said third liquid phase in a fourth separation zone at atemperature above about 700 F. and at a subatmospheric pressure toprovide a residuum fraction containing those hydrocarbons boiling aboveabout 1050 F. and a heavy gas oil fraction boil: ing below about 1050F.; and, (e) introducing at least a portion of said heavy gas oilfraction into said third separation zone at a point above said meshblanket.

Other embodiments of our invention reside in particular operatingconditions and in the use of various internal recycle streams. Thequantity of heavy gas oil being introduced into the third separationzone, herein referred to as the hot flash zone, is within the range offrom 1.0% to about 10.0% by volume of the total heavy gas oil produced.An intermediate and generally preferred range is from about 3.0% toabout 8.0%. Also, a portion of the first liquid phase is recycled tocombine with the conversion product eflluent, prior to separation in thefirst separation zone which is herein referred to as a hot separator.The hot separator is maintained at essentially the same pressure as theconversion product effluent, and this pressure is nominally in the rangeof from about 1000 p.s.i.g. to about 4000 p.s.i.g. The preferredtemperature of the product efiiuent entering the hot separator is belowabout 750 F. At temperatures above 750 F., heavier normally liquidhydrocarbons tend to be carried over into the first vapor phase, whileat temperatures below about 700 F., ammonium salts, from the conversionof nitrogenous compounds, tend to fall into the liquid phase. Therefore,that portion of the first liquid phase being recycled to combine withthe product efiluent, is first utilized as a heat-exchange medium to theextent necessary to lower its temperature to a level such that thecombined charge to the hot separator is at a temperature generally inthe range of from 700 F. to about 750 F.

The second separation zone, herein referred to as a cold separator.Although functioning at essentially the same pressure as the producteffluent and hot separator, is maintained at a temperature of from about60 F. to about 140 F. The pressure levels maintained upon the third andfourth separation zones are substantially reduced from the pressureunder which the hot and cold separators are maintained. The maximumpressure on the third separation zone will be about 200 p.s.i.g., andthis zone will function at an elevated temperature somewhat less thanthe temperature of the first liquid phase emanating from the hotseparator. Preferably, the fourth separation zone is operated as avacuum column at a subatmospheric pressure less than about mm. of Hg.The third liquid phase, intended to be introduced into the vacuum columnmay be at a temperature less than about 700 F., and is, therefore,heated to a temperature above 700 F. with an upper limit of about 900F., prior to being introduced into the vacuum column.

Prior to discussing the present process in detail, and especially inconjunction with the accompanying drawing, several definitions ofvarious terms and phrases are believed necessary for a clear andcomplete understanding. References to boiling points and temperatureranges of various hydrocarbons, and mixtures of hydrocarbons, are thoseobtained through the use of ASTM Standard Distillation Methods.Likewise, the phrase hexane-400 F. is intended to mean a normally liquidstream boiling below a temperature of 400 F. and including heXanes.Similarly, the term 650 F.-plus connotes a liquid stream containingthose hydrocarbons boiling at 650 F. and above.

The phrase gasoline boiling range hydrocarbons, is intended to includenormally liquid hydrocarbons boiling up to about 400 F. It is understoodthat the upper temperature limit, or end boiling point, of gasolinevaries from locale to locale, and is, therefore, considered to be 425 F.or 450 F. For present purposes, however, normally liquid gasolinehydrocarbons is intended to include butanes and have a nominal endboiling point of 400 F.

A pressure substantially the same as, is intended to indicate that thepressure imposed upon a particular vessel is that pressure imposed uponan upstream vessel, allowing only for the normal pressure loss due tofluid flow through the system from one vessel to the other. Also, atemperature substantially the same as, is used to show that anyreduction in temperature stems from normally experienced radiationlosses due to the flow of material or from the conversion of sensible tolatent heat by flashing where a pressure drop occurs.

The process can be further characterized in that the hot separator isemployed primarily to provide a first vapor phase substantiallycompletely free from l050 F.-plus material, concentrating the latter ina first liquid phase. The cold separator, operating at substantially thesame pressure as the hot separator, but at a lower temperature in therange of 60 F. to F., serves to concentrate the hydrogen in thecondensed first vapor phase. As hereinafter indicated, a hydrogen-richsecond vapor phase, comprising about 82.5 mol percent hydrogen, and onlyabout 2.3 mol percent propane and heavier hydrocarbons, is madeavailable for use as a recycle stream to be combined with the freshblack oil charge stock. The liquid phase from the cold separatorcomprises about 66.7% by volume of butanes and heavier hydrocarbons, andonly about 1.9 volume percent boiling in the range of 650 F. to 1050 F.

The hot flash zone functions at a temperature substantially the same asthe hot separator, but at a significantly reduced pressure less than 200p.s.i.g. This vessel serves primarily to concentrate the 400 F.-plushydrocarbons in a third liquid phase, while also producing a thirdvaporo-us phase substantially free from the 1050" F.-plus material andcontaining only a minor amount of 650 F.-1050 F. hydrocarbons. In orderto ensure that none of the unreacted asphaltics present in theconversion product effluent contaminate the material of the third vaporphase, with the consequence that various downstream fractionationfacilities become plugged the hot flash zone is supplied with a meshblanket, or de-mister screen, below which the first principally liquidphase, from the hot separator is introduced. Since the hot flash zone isoperated at a significantly reduced pressure-Le. from about 2600p.s.i.g. down to 65 p.s.i.g.-and at a temperature slightly less thanabout 750 F., the material entering the vessel is flashed with theresult that asphaltics have the tendency to be carried overhead with thethird principally vaporous phase. Since subsequent separation andfractionation facilities will be maintained at significantly lowertemperatures, the continual flashing of these asphaltics ultimatelyresults in plugged lines and heatexchange equipment, etc. To counteractthis, a mesh blanket is inserted, or disposed, within the hot flash zoneat a locus above the point where the first liquid phase is introduced.The flashed asphaltics are unable to pass through the screen, and thusdo not contaminate" the material boiling up to about 1050 F., therebyavoiding misoperation of subsequent facilities employed to separate theproduct into the desired fractions.

The third liquid phase, containing more than 95.0 mol percent 400F.-plus material, is further separated to concentrate the asphaltics ina residuum fraction and to prepare a wash oil employed to continuouslyremove the trapped asphaltics from the mesh blanket disposed in the hotflash zone. As hereinafter indicated in describing the drawing, this isperhaps best accomplished through the use of a vacuum column operatingat a subatmospheric pressure of 100 mm. of Hg, or less. In this manner,the asphaltic residuum is recovered as a separate bottoms streamsubstantially free from distillable hydrocarbons. More importantly, theproper kind or type of wash oil is readily prepared. Since the hot flashzone is functioning at a temperature of from 700 F. to somewhat lessthan 750 F. due to heat loss in transferring material from the hotseparator, the wash oil itself should be one which is normally liquid atthis temperature. That is, it should be of the character which may becondensed in the upper region of the hot flash zone (above the meshblanket) so that, as a heavy liquid stream, it will tend to pass downthrough the mesh blanket and be removed with the liquid phase. In sodoing, the wash. oil, which has a high capacity for the asphaltics,removes them from the mesh blanket, and carries them into the vacuumcolumn wherein they are removed from the process as the residuum. Thewash oil prepared by the present process may be characterized as a heavygas oil, or, since the use of a vacuum column as the fourth separationzone is preferred, as a heavy vacuum gas oil (-HVGO). The amountemployed by way 'of recycle to the hot flash zone, at a point above themesh blanket, is from 1.0% to about 10.0% by volume of the total heavygas oil produced. By way of definition, a heavy vacuum gas oil is thehigher boiling 70.0% to about 80.0% by volume portion of the total gasoil, the latter including that portion considered in the art as a lightvacuum gas oil (LVGO). A commonly referred to boiling range for gas oilis an initial boiling point of 650 F. and an end boiling point of about1050 F. The higher boiling 70.0% to 80.0% thereof, the heavy gas oil,characteristically is considered as having an initial boiling point ofabout 750 F. It is, of course, recognized that a light vacuum gas oilcan have an initial boiling point as low as 500 F. and an end boilingpoint as high as about 800 F. Similarly, the heavy vacuum gas oil canhave an initial boiling point as low as 700 F.

Thus, the separation process herein described, and as illustrated in theaccompanying drawing, results in five different, principal productstreams. A first product stream is a principally gaseous phasecontaining more than about 80.0% by volume of hydrogen; it is,therefore, advan tageously utilized as a recycle stream. to supply aportion of the hydrogen required in the conversion zone. A second,principally liquid product stream is obtained by combining the secondliquid phase from the cold separator and the third vapor phase(preferably after being suitably cooled) from the hot flash zone, andcomprises more than about 60.0% butanes and heavier hydrocarbons. Ashereinafter indicated, this stream can be conveniently treated and/orfractionated in order to recover various component fractions thereof.

A third product stream is the heavy vacuum gas oil, a

portion of which is recycled as Wash oil to the hot flash zone. Theremainder may be, Where desired, combined with the fourth product streamwhich is the light vacuum gas oil fraction. Obviously, the fifth productstream is the as phaltic residuum.

From the foregoing brief description, it will be readily ascertained bythose possessing skill in the art of petroleum processing techniques,that the present invention comprises a series of integrated steps forthe separation of a mixedphase reaction product efiiuent, resulting froma black oil conversion process, in an easy and economical manner. Theconversion of black oils is generally intended to accomplish primarilytwo objects: first, to desulfurize the black oil to the extent dictatedby the desired end result, whether maximizing fuel oil, or gasolineboiling range hydrocarbons; secondly, it is intended to producedistillable hydrocarbons, being those normally liquid hydrocarbonsincluding pentanes, and for present purposes butanes, having boilingpoints below about 1050 F. The conversion conditions are intended toinclude temperatures above about 600 F., with an upper limit of about800" E, as measured at the inlet to the fixed-bed of catalyst disposedwithin the reaction zone. Since the bulk of the reactions being effectedare exothermic, the reaction zone effluent will be at a highertemperature. In order that catalyst stability be preserved, it isgenerally preferred to control the inlet temperature at a level suchthat the temperature of the reaction product effluent does not exceed950 F. Hydrogen is admixed with the black oil charge stock, by means ofcompressive recycle, in an amount usually less than about 10,000s.c.f./bbl., at the selected operating pressure; the hydrogen is presentin the recycle gaseous phase preferably in an amount of about 80.0% ormore. A preferred range of the quantity of hydrogen being admixed withthe fresh black oil charge stock is from about 3000 to about 8000s.c.f./bbl. The conversion reaction zone will be maintained at apressure greater than about 1000 p.s.i.g., generally with an upper limitof about 4000 p.s.i.g. The black oil passes through the catalyst at aliquid hourly space velocity (defined as volumes of liquid hydrocarboncharge per hour, as measured at 60 P., per volume of catalyst disposedwithin the reaction zone) of from about 0.25 to about 2.0.

As herein-before set forth, hydrogen is employed in admixture with thecharge stock, and preferably in an amount of from about 3000-to about8000 s.c.f./bbl. The hydrogencontaining gaseous phase, herein sometimesdesignated as recycle hydrogen since it is conveniently recycledexternally of the conversion zone, fulfills a number of variousfunctions; it serves as a hydrogenating agent, a heat carrier, andparticularly a means for stripping converted material from thecatalytically active sites for the incoming, unconverted hydrocarboncharge stock. In view of the fact that some hydrogenation will beeffected, there will be a net consumption of hydrogen; to supplementthis, hydrogen must be added to the system from a suitable externalsource. The catalytic composite disposed within the reaction zone can becharacterized as comprising a metallic component possessinghydrogenation activity, which component is composited with a refractoryinorganic oxide carrier material which may be of either synthetic ornatural origin. The precise composition and method of manufacturing thecatalytic composite is not considered to be an essential element of thepresent process.

Other conditions and preferred operating techniques will be given inconjunction with the following description of one embodimentincorporating the separation process of the present invention. Infurther describing this process, reference will be made to theaccompanying figure which is presented for the sole purpose ofillustration. In the drawing, the embodiment is presented by means of asimplified flow diagram in which such details as pumps, instrumentationand controls, heat-exchange and heat-recovery circuits, valving,start-up lines and similar hardware have been omitted as beingnon-essential to an understanding of the techniques involved. The use ofsuch miscellaneous appurtenances, to modify the illustrated processflow, are well within the purview of those skilled in the art.

For the purpose of demonstrating the illustrated embodiment, and theutilization therein of the process of the present invention, the drawingwill be described in connection with the conversion of a vacuum residuumhaving a gravity of 8.8 API at 60 F., and an ASTM 20.0% volumetricdistillation temperature of 1055 F. In addition, the description will bedirected toward a commerciallyscaled unit having a capacity of about10,000 bbL/day of fresh charge. It is to be understood that the chargestock, stream compositions, operating conditions, design offractionators, separators and the like are exemplary only, and may bevaried widely without departure from the spirit of my invention, thescope of which is defined by the appended claims. Other charge stockproperties are presented in the following Table I:

TABLE I.--VACUUM RESIDUUM PROPERTIES Gravity, API at 60 F. 8.8Distillation, D1160, F.:

Initial boiling point 690 2% 860 950 1000 20% 1055 Sulfur, wt. percent3.0 Nitrogen, total ppm. 430 Heptane insolubles, wt. percent 6.5

This vacuum residuum is intended to be converted into 80.0% by weight ofhydrocarbon products recoverable by standard distillation in commonlyused fractionation facilities. Furthermore, it is intended that thisobject be accomplished with minimal production of methane and ethane,and minimal loss of propane as a gaseous waste product. Obviously, acorollary object is to maximize the recovery of normally liquidhydrocarbons, inclusive of butanes. The vacuum residuum is processed ina fixedbed catalytic conversion zone in admixture with 5000 s.c.f./bbl.of hydrogen, at an inlet pressure of about 2700 p.s.i.g. and an inlettemperature of about 800 F. The liquid hourly space velocity, based uponfresh liquid feed only, is 0.5, and the combined feed ratio with respect to total liquid feed is 2.0.

With reference now to the drawing, the black oil conversion producteflluent, in mixed phase and containing about 9.4% by Weight ofasphaltic residuum, is introduced into hot separator 3 via line 1, andafter being admixed with hot separator recycle in line 2, the source ofthe latter hereafter set forth. The conditions of the product effluent,at the outlet of the conversion zone are a temperature of about 875 F.and a pressure of about 2550 p.s.i.g. Prior to entering hot separator 3,the 313,000 lbs/hr. of conversion zone effluent is employed as aheat-exchange medium in order to lower its temperature, and is thencombined with 142,000 lbs/hr. of hot separator recycle. The latter,after use as a heatexchange medium, exists at a temperature of about 400F. The temperature, therefore, of the total material entering separator3 is about 750 F., the pressure being about 2.535 p.s.i.g. A principallyvaporous phase, in an amount of about 60,500 lbs/hr. is removed via line4 into condenser 5, while a total of about 134,000 lbs/hr. is recycled,while hot (about 875 F.), to combine with the fresh charge stock to theconversion zone. However, since this does not constitute an essentialelement of our separation process, this recycle system is notillustrated in the drawing. As previously set forth, 142,000 lbs/hr. isdiverted through line 2, and after use as a heatexchange medium, wherebyits temperature is lowered to about 400 F., continues therethrough tocombine with the conversion product etlluent in line 1.

In the following Table II, the analyses of the various streams involvedin the function and operation of hot separator 3 are presented. Forconvenience, the quantitles are given in mols/hr. for the conversion forthe product elrluent entering the hot separator (line 1), for the firstvapor phase (line 4) and for the net liquid phase to the hot flash zone12 (line 11).

TABLE II.HOT SEPARATOR STREAM ANALYSES Line No 1 4 11 Component,mols/hr.:

Ammonia 17 17 Nitrogen 31 29 1.0 Hydrogen Sulfide 247 217 13. 7 Hydrogen4, 125 3, 834 160.0 Methane 594 539 26. 4 Ethane. 129 108 9. 8 Propane.93 8. 5 Butane. 68 55 6. 2 Pentane 31 23 3. 4 Hexane, 400 F 148 93 26. 5400 F.650 F. 215 53 75. 8 650 F.1,050 F.-. 308 5 142. 4 1,050 F. plus 9645. 2

Totals 6, 169 5, 066 518. 9

No analysis is given for the hot separator recycle stream in line 2;this material remains substantially unchanged, the actual amount beingdetermined on the basis of the temperature of the total materialentering hot separator 3.

The vaporous phase in line 4, 60,500 lbs./hr., is com densed incondenser 5, and passes through line 6 into the cold separator 7. In theinstant illustration, the material removed as the sour water stream isin the amount of about 370 lbs./hr., exclusive of the wash water.

A hydrogen-rich gaseous phase, in an amount of 27,900 lbs./hr., iswithdrawn from separator '7 through line 8, via compressive means notshown, and is recycled thereby to the conversion reaction zone. A netliquid phase, in the amount of 32,230 lbs./hr., is withdrawn throughline 9. In the following Table III, component stream analyses are givenfor the hydrogen-rich gaseous phase (line 8) and the second principallyliquid phase (line 9).

TABLE TIL-COLD SEPARATOR STEAM ANALYSES LineNo 8 9 Component, mols/hrAmmonia. N itrogen Hydrogen Hexane, 400 F 400 F-650 F 650 F1,050 1,050 Iplus Totals As indicated in the table, cold separator 7 produces agaseous phase comprising about 82.5 mol percent hydrogen. It should benoted too that this stream contains only about 2.3% by volume of propaneand heavier hydrocarbons. Analysis further indicates that the endboiling point of the hexane-400 F. material is 300 F.

The first liquid phase in line 11 continues therethrough into hot flashzone 12 having disposed therein mesh blanket 13. The material, at atemperature of about 735 F. is introduced at a point below mesh blanket13. Also introduced into hot flash zone 12, at a point above meshblanket 13, is 2,135 lbs/hr. of a heavy vacuum gas oil in line 18, thesource of which is hereafter described. A third principally vaporousphase is withdrawn via line 10, in the amount of 18,400 lbs./ hr., andis admixed with the liquid phase in line 9 as one of the product streamsof the present process. A third liquid phase, in the amount of 102,135l'bs./hr., containing the unreacted asphaltics, is removed via line 14,and passes therethrough into vacuum column 15. In the following TableIV, component stream analyses are given for the vaporous phase from thehot flash zone (line 10) and the liquid phase (line 14) which passesinto vacuum column 15. Included in the latter is the 4.4 mols/hr. (2,135lbs/hr.) of HVGO which is introduced above mesh blanket 13. Forconvenience, the analysis of the mixture of the second liquid stream(line 9) and the vapor phase (line 10) is indicated in the table as line9-10.

TABLE IV.HOT FLASH ZONE STREAM ANALYSES Line No 10 14 9-10 Component,mols/hr.:

Ami-non Nitrogen 1. 3. 0 Hydrogen Sulfide. 13. 0. 2 94. 5 Hydrogen 158.4 1. 6 292. 4 Methane 26. 1 O. 3 113. 1 Ethane.-. 9. 5 0.3 43. 5 Propane8. 2 0. 3 43. 2 Butane 5. 9 0.3 30. 9 Pentane- 3. 2 0.2 17. 2 Hexane,400 23. 0 3. 5 109. 0 400 F.650 F. 40. 4 35. 4 93. 4 650 F.1050 Fl 11. 0135. 8 16.0 1050 F. plus 45. 2

Totals: 300. 2 223. 1 856. 2

It should be noted, from the data presented in Table IV, that theproduct stream combined as lines 9 and 10 is free from hydrocarbonaceousmaterial boiling above about 1050 F. Also, the liquid stream in line 14comprises only 1.4 mol percent of propane and lighter gaseousconstituents. With respect to the product stream combined as lines 9 and10, it will be recognized that this product may be further separated,probably after being condensed, to further concentrate the normallyliquid hydrocarbons such that they may be fractionated without thedifliculties attendant vapor loading of the columns.

The principally normally liquid stream in line 14 is heated to atemperature of about 825 F., and is introduced into vacuum column 15maintained under a subatmospheric pressure of about 50.0 mm. of Hg,absolute. A heavy vacuum gas oil, in an amount of 57,635 lbs./hr., or118.5 mols/ hr. is withdrawn via line 18. Of this amount, 4.4 mols/hr.(2,135 lbs/hr.) or about 3.7% by volume thereof, continues through line18, being introduced thereby into hot flash zone 12 at a point abovemesh blanket 13. The remaining portion, 55,500 lbs./hr., is divertedthrough line 19 as the HVGO product. The asphaltic material, in anamount of about 29,400 lbs./hr., is removed via line 16. A light vacuumgas oil, in an amount of about 15,000 lbs/hr. is removed via line 17.The vacuum column gas to the jets, not illustrated in the drawing,amounts to about 100 lbs./hr., and comprises the pentane and lighterportion of the material in line 14. The following Table V indicates thecomponent stream analyses for the HVGO recovered as a product (line 19)and the LVGO product (line 17).

TABLE V.VAOUUM COLUMN STREAM ANALYSES Line No 17 19 Component, mole/hmHexanes, 400 F 3. 5 400 1 .-650 F- 35.4 650 F.-1, 050 F 17. 3 114. 1 1,050 F. plus- Totals 56. 2 114. 1

10 from 650 F. to 750 F. and 30.8% from 750 F. to 850 F.

The 3.7% by volume of HVGO which continues through line 18 as wash oilfor the mesh blanket 13 has the same component composition given abovefor the HVGO product. The successful application thereof in keeping themesh blanket clean is indicated by the fact that the 650 F.-1050 F.portion of the third vaporous phase in line 10 (11.0 mols/hr.) comprises69.0% by volume of hydrocarbons boiling from 650 F. to 750 F., 25.4%boiling from 750 F. to 850 F., 4.6% from 850 F. to 950 F. and about 1.0%from 950 F. to 1050 F. As indicated in the foregoing Table IV, thisstream does not contain hydrocarbons boiling about 1050 F.

The foregoing specification, and particularly the description of theaccompanying drawing, indicates the separation process of the presentinvention, as adapted to black oil processing, and clearly shows themethod by which the internally recycled wash oil is prepared.

We claim as our invention:

1. A process for separating a mixed-phase hydrocarbonaceous conversionproduct efiluent containing hydrocarbons boiling above about 0 F., whichprocess comprises the steps of:

(a) separating said product efiiuent in a first separation zone at atemperature above about 700 F. and a pressure above about 1000 p.s.i.g.,to provide a first vapor phase and a first liquid phase;

(b) condensing said first vapor phase and separating the condensedvapors in a second separation zone at a temperature below about F. and apressure substantially the same as said first separation zone, toprovide a hydrogen-rich second vapor phase and a second liquid phaseprincipally comprising propane and heavier normally liquid hydrocarbons;

(c) introducing at least a portion of said first liquid phase into athird separation zone at a point below a mesh blanket disposed withinsaid third separation zone, at a temperature substantially the same assaid first separation zone and at a pressure less than about 200p.s.i.g., to provide a third vaporous phase and a third liquid phasecontaining hydrocarbons boiling above 1050 F.;

(d) further separating said third liquid phase in a fourth separationzone at a temperature above about 700 F. and at a subatmosphericpressure to provide a residuum fraction containing those hydrocarbonsboiling above about 1050 F. and a heavy gas oil fraction boiling belowabout 1050 F.; and,

(e) introducing at least a portion of said heavy gas oil fraction intosaid third separation zone at a point above said mesh blanket.

2. The process of claim 1 further characterized in that the portion ofsaid heavy gas oil introduced into said third separation zone is in anamount of from about 1.0% to about 10.0% by volume of said heavy gas oilfraction.

3. The process of claim 1 further characterized in that the temperatureof said first separation zone is within the range of from about 700 F.to about 750 F., and the pressure is within the range of from about 1000p.s.i.g. to about 4000 p.s.i.g.

4. The process of claim 1 further characterized in that said secondseparation zone functions at a temperature of from about 60 F. to about140 F., and a pressure of from about 1000 p.s.i.g. to about 4000 p.s.ig.

5. The process of claim 1 further characterized in that said fourthseparation zone functions at a subatmospheric pressure less than 100 mm.of Hg.

No references cited.

HERBERT LEVINE, Primary Examiner.

1. A PROCESS FOR SEPARATING A MIXED-PHASE HYDROCARBONACEOUS CONVERSIONPRODUCT EFFLUENT CONTAINING HYDROCARBONS BOILING ABOVE ABOUT 1050*F.,WHICH PROCESS COMPRISES THE STEPS OF: (A) SEPARATING SAID PRODUCTEFFLUENT IN A FIRST SEPARATION ZONE AT A TEMPERATURE ABOVE ABOUT 700*F.AND A PRESSURE ABOVE ABOUT 1000 P.S.I.G., TO PROVIDE A FIRST VAPOR PHASEAND A FIRST LIQUID PHASE; (B) CONDENSING SAID FIRST VAPOR PHASE ANDSEPARATING THE CONDENSED VAPORS IN A SECOND SEPARATION ZONE AT ATEMPERATURE BELOW ABOUT 140*F. AND A PRESSURE SUBSTANTIALLY THE SAME ASSAID FIRST SEPARATION ZONE, TO PROVIDE A HYDROGEN-RICH SECOND VAPORPHASE AND A SECOND LIQUID PHASE PRINCIPALLY COMPRISING PROPANE ANDHEAVIER NORMALLY LIQUID HYDROCARBONS; (C) INTRODUCING AT LEAST A PORTIONOF SAID FIRST LIQUID PHASE INTO A THIRD SEPERATION ZONE AT A POINT BELOWA MESH BLANKET DISPOSED WITHIN SAID THIRD SEPARATION ZONE, AT ATEMPERATURE SUBSTANTIALLY THE SAME AS SAID FIRST SEPARATION ZONE AND ATA PRESSURE LESS THAN ABOUT 200 P.S.I.G., TO PROVIDE A THIRD VAPOROUSPHASE AND A THIRD LIQUID PHASE CONTAINING HYDROCARBONS BOILING ABOVE1050*F.;